Shrinking of textile yarns and like materials



Nov.` 13, 1945. F.,B. H1L| Erm.

SHRINKING 0F TEXTILE YARNS AND LIKE MATERIALS Filed March 27, 1942 Amr/mls Patented No 13, 1945 SHRINKING F TEXTILE YARNS AND LIKE MATERIALS Frank Brentnall Hill and William Harry Kimpton,

Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware Application March 27, 1942, Serial No. 436,392

In Great Britain April 9, 1941 4 Claims. -(Cl. 8-132) This invention relates to the shrinking of textile yarns and like materials such as filaments, ribbons or the like, for the purpose of improving their properties, and is particularly concerned with the shrinking of such materials for the purpose of increasing their extensibility.

As is well known, a certain degree of the ex- Y tensibility, e. g. lil-15% or more, is desirable in such textile materials for the purposes of knitting, Weaving and other operations, as also in the products resulting from such operations. Certain materials, however, do not possesses much extensibility as isdesirable. For example artificial yarns of cellulose acetate or other cellulose ester which have been stretched with or without the aid of a softening medium for the purpose of increasing their tensile strength, as described in U. S. Patent No. 1,709,470, are apt to possess a low extensibility. Again, in the wet spinning of cellulose esters or ethers as described in U. S. Patents Nos. 1,465,994, 1,467,493, 2,147,640, 2,179,544 and 2,086,122, the iilaments produced', though of high tenacity, may be of low extensibility, In order to increase their extensibility, such materials may be submitted to a shrinking treatment in which, conveniently, the materials are run under little or no tension through a bath of shrinking agent. In order to avoid excessive tenson in the materials under the influence of the shrinking agent, which tension might inhibit the desired shrinkage, the materials may be positively fed into the bath, as well as positively removed therefrom, so that the materials, While in the bath, are relieved of the tension necessary to draw them from their source of supply and through the necessary guides to the point Where they enter the bath. Quite a small degree of tension, however, is sometimes enough tointerfere with the shrinking of the materials, and even when the above precautions are taken, the frictional resistance of the liquid in the bath to the passage ofthe materials through the bath may be suilicient to have a harmful eiect. It is an object of` the present invention to provide a method and means that are simple, eiective and inexpensive, for preventing the development of undue tension on the materials in the shrinking bath.

According to the present invention textile yarns and like materials are submitted to a shrinking operation by being fed into a liquid shrinking agent for the materials ata controlled rate, and withdrawn from said agent at a controlled rate lower than the rate of feeding, so as to allow the materials to shrink, said agent being caused toA iiow in the same direction and with substantially 4the same mean speed as the materials. t In this way the application to the materials, while they are shrinking, of tension due to friction with the shrinking liquid is substantially avoided since little or no relative motion between the liquid and the materials takes place.

A convenient way of securing the desired ow of shrinkingv liquid is to incline the bath in which it is contained, and to supply liquid at the upper end of said bath so that the liquid runs under gravity with the materials being treated in the bath. The angle to the horizontal at which the bath should be inclined will depend upon the means speed of the materials running through the bath and the depth of liquid that it is necessary to provide.' s

The bath in which the shrinking treatment takes place is preferably in the form of a V- sectioned groove or trough, the material being fed into the trough at one end and removed from the trough at the other either by means of rollers, e. g. nip rollers, or by means of V-grooved pulleys the lower part of each of which is below the level of the liquid in the trough. By the use of a V-sectioned trough in this manner, the volume of liquid flowing with the materials along the length of the bath is reduced, While at the same time a substantial depth of liquid isrprovided-below the surface of which the materials to be treated may run. Several of such V-sectioned troughs may be formed side by side, by folding or corrugating' a sheet of metal and may be served at each end by a pair of nip rollers of suitable length, or by a corresponding number of grooved pulleys mounted on a common shaft.

Since, in consequence of shrinking, the materials leave the bath at a smaller linear speed than that at which they enter it, there is a diminution in the speed of the filaments from one end of the bath to the other. The slope of the bath and the depth of liquid therein may be so adjusted that the liquid flowing through the bath slows down in a corresponding manner. In order to achieve this, and indeed in any case, it is preferable that the liquid should lcome into contact with the materials with a speed substantially equal to that of the materials, i. e. the velocity desired of the liquid should be imparted to it before it cornes in contact with the materials. In this way the inclination of the bath only provides for the maintenance of the velocity vof the liquid and'is not concerned with imparting a velocityto the liquid.

By imparting to the liquid a suitable velocity before it comes into contact with thevrnaterial,

the additional advantage is obtained that turbulence in the liquid as it engages with the material,

or with pulleys controlling the material is avoided, or substantially reduced, since there is little relative velocity between the liquid and the material or the submerged part of the pulleys to set up turbulence. Additional precautions to avoid turbulence, however, may be taken. Thus, Where pulleys are used, at the end of the bath where the materials enter the bath the liquid may be fed into the bath at a po'int some distance beyond the pulley by which the rate of entry of the materials is controlled, so that the liquid and the pulley never come into contact with one another and no turbulence can arise from such contact. Similarly at the end of the bath where the materials leave the bath, the pulley may be disposed beyond the end of the bath, the liquid after running along the length of the bath, emerging freely from the end of the bath and falling away from the materials, which proceed to the grooved pulley by which they are controlled.

While the invention is capable of ,general application to the shrinking of textile yarns, and like materials, having a low extensibility it is particularly applicable to artificial yarns of cellulose acetate or other organic derivatives of cellulose which have been submitted to a stretching operation for the purpose of improving their tenacity.

As suitable shrinking agents for use in connection with the present invention there may be employed any organic substances, or solutions or mixtures of organic substances which have a swelling action upon the material to be shrunk, for example, where the material is a cellulose derivative, the substances referred to as shrinking agents in U. S. Patent No. 2,058,422. As mentioned in that specification it is particularly advantageous to employ agents which, at least at ordinary temperatures, are incapable of dissolving the cellulose derivative but which are capable of swelling the cellulose derivative in a high degree. Examples of such agents suitable for use in connection with commercial acetone-soluble cellulose acetate are methylene chloride, ethylene chloride,` chloroform, tetrachlorethane, ethyl alcohol and the like, these liquids being preferably employed in conjunction with a suitable diluent such as those described in U. S. Patent No.

Two forms of apparatus suitable for carrying l out the present invention will now be described standards 4, one on each side of the frame, eachA the sheet. the rod 8 extending through the curved slots 5 in the standards 4 and being secured in any desired position therein so that the corrugated sheet 6 slopes downwards towards the pivot shaft.

At each end of the corrugated sheet 6 are secured suitable brackets i, l I, II) being at the lefthand or upper end and II at the right-hand or lower end of the sheet 6, each bracket carrying a pair of contacting nip rollers I2, i3; i4, I5 carried on shafts journalled in the brackets. The pressures between the pair oi rollers i2, I3, and between the pair of rollers I4, I5 may be adjusted by means of screws I6 mounted in the brackets I0, II. 'I'he rollers I2, I3 are connected, by means of a chain 20 passing round sprockets 2|, to a change speed gear 24 of the positive and infinitely variable kind. Similarly, the rollers I4, I5 are connected by means of a chain 2l) and sprockets 2| to a similar change speed gear 25. By the provision of separate innitely variable drives 24 and 25 for the two ends of the machine the ratio of the input and output speeds may be adjusted to accommodate any degree of shrinkage that may occur. Idler pulleys 22 and 26, adjustably mounted to slots 23, 2l, are provided to adjust the tension in the chains 2D. Into each of the V shaped grooves in the sheet 6 extends a supply pipe I1 for the shrinking fluid, the several supply pipes I I branching from a. main feed pipe or header I8.

In the operation of the machine a sheet of threads 28 are treated simultaneously, the threads being preferably equal in number to the number of V-shaped grooves in the sheet 6, though two or more threads may be simultaneously treated in each groove if desired. The threads 28, in sheet `form, are passed over the roller I2, through the nip between the rollers I2 and I3 and under the roller I3, by which they are led directly into the V-shaped corrugations in the sheet li, passing into having a curved slot 5 struck about the pivot y shaft 2 as a centre. 'Pivotally mounted on the shaft 2 is a corrugated sheet ofimetal 6 the corrugations forming deep V-shaped grooves, of the form shown in Figure 5, extending along the sheet in a'direction at right angles to the pivot shaft 2 on which the lsheet is mounted. The other I, end of the corrugated sheet is supported on a rod 8 disposed beneath the plate 9 serving toJreinforce the corrugations immediately below the feed pipes Il by means of which the shrinking fluid is supplied. The threads pass along the length of the sheet 6kand emerge at the other end, being guided therefrom by means of the roller I4which is disposed as close as possible to the lower end oi' the sheet 6. The threads pass under the roller I4, through the nip between the rollers I4, I5, and over the roller I5, from which they are conducted over suitable drying means to a winding creel lwhere they are collected. Shrinking liquid is fed through the main feed pipe or header I8 and so by way of the pipes I'I to the individual grooves, the rate offeed being such that the velocity of the shrinking liquid is substantially equal to the velocity of the materials being treated. The inclination of the corrugated sheet 8 is adjusted by means of the curved slots 5 in the vertical standards 4 at one end of the machine, so that the initial velocity of the shrinking liquid is substantially maintained along the length of the sheet 6..'

When the shrinking liquid reaches the lower edge of the sheet 6 it simply runs out at the ends o! the corrugations and is collected in a suitable vessel orconduit for further use. If the roller I4 is disposed close to the lower edge of the 'sheet 4 the threads are prevented by the roller I4 from being drawn downwards with the emerging stream of shrinking fluid.

Figures 2-5 show a modiiication of the apparatus described with reference to Figure 1 in which grooved pulleys are employed to conduct the threads 28A into the V-shaped channels of the sheet 8. Figure 2 shows the input end of the machine in which a pulley 30 having a'groove l of V-section round its periphery is mounted on a shaft 3I carried onbrackets 32 secured to a plate 33 serving the same purpose 'as the plate 9 described with reference to Figure 1. Similarly, Figure 3 shows the output end of the machine wherein a V-grooved pulley 38 is mounted on a shaft 39 carried in a bracket 40. The rollers I4 and I5 in Figure 3 are carried on a separate bracket 4I secured to the frame I, instead of in a bracket secured, like the bracket II of Figure 1, to the lower end of the sheet 6. A In both Figure 2 and Figure 3 the drive of the nip rollers is modified, the three shafts carrying the rollers I2,

I3 and the pulleys 30 being connected together by means Vof a chain 34 passing round the 'idler sprocket 22, while a sprocket 36 is provided on the pulley shaft round which the driving chain 2li from the change speed gear 24 passes. Similar arrangements are made at the output end of the machine as shown in'Figure 3.

In Figure 2 the threads 28 pass under the roller I3, over the roller I2 and downwards to the V-section grooves in the pulleys 30 which lead the threads into the V-channels of the plate 6 at a point some distance from the edge of the plate. As shown in Figures 4 and 5, the ends of the V-channels are closed by means of V-shaped blocks 42 through which the supply pipes I'I pass, each supply pipe II leading into an enlarged mouth 43 formed in the block 42..

In order to control the flow of liquid and to prevent splashing and disturbance of the liquid by the pulleys ,30, cheeks 44, each part-cylindrical in form are provided on the inner faces of the V-channels, the cheeks 44 being of a length approximately equal to the diameter of the pulleys 3B and sloping downwards from the neighbourhood of the mouth 43 to the bottom of the bath. The cheeks 44 thus run close to the side faces of the pulleys 30 as shown in Figure 5.

As an example of the sort ofvtr'eatment that may be effected by means of either of the forms of apparatus described above, the following is given:

Example Having described our invention what we desire to secure by Letters Patent is:

l. A method'of shrinking unassociated cellulose derivative textile yarns Icomprising feeding the yarns at a controlled rate into the upper end of a sloping bath containing a liquid shrinking agent for the yarns and withdrawing the yarns from the lower end of said bath at a controlled Y 'of a sloping 'bath containing a 1iquid which,

withdrawing the yarns from the lower end of Cellulose acetate yarn having a low extensibility and a high tenacity as a result of a previous operation of stretching in the presence of a drying .operation by means of which the excess shrinking liquid entrained with the yarn is driven o by evaporation.

though incapable of dissolving the cellulose derivative yarns is a. swelling agent therefor, and

said bath at a controlled rate that is lower than the rate of feeding, the slope of said bath being such as to cause saidagent to flow under gravity with substantially the same mean speed as the yarns, so as to allow said yarns to shrink while substantially free from tension due to oontat with said swelling agent.

3. A method of treating unassociated cellulose derivative textile yarns comprising stretching the yarns so as to increase their tensile strength, and then shrinking the yarns by feeding them at a controlled rate into the upper end of a sloping bath containing a liquid shrinking agent for the yarns and withdrawing the yarns from the lower end of said bath at a controlled rate that is lower than the rate of feeding, the slope of said bath being such as to Icause said agent to flow under gravity with substantially the same mean speed as the yarns, so as to allow said yarns to shrink while substantially free from tension due to contact with said shrinking agent.

4. A method of treating unassociated cellulose acetate t'xtile yarns comprising stretching the yarns in the presence of a softening agent therefor so as to increase the tensile strength of the yarns, and then shrinking thel yarns by `feeding them at a controlled rate into the upper end of a sloping bath containing a liquid which though not capable of dissolving cellulose acetate is a swelling agent therefor -and withdrawing the yarns from the lower end of said bath at a controlled rate that is lower than the rate of feeding. the slope of said bath being such as to cause said agent to -fiow under gravity with substantially the same mean speed as the yarns, so as to allow said materials to shrink while substantially free from tension due to contact with said swelling agent.

` FRANK BRENTNALL HILL.

WILLIAM HARRY KIMPTON.

' CERTIFICATE 0F coRREcTIoN. v Patent No` 2,588,7-l2. November 15, 19,45.

FRANK BRENTNALL HILL, ET AL.

It `is hereby certified that error appears in the printed specification' of the above numbered patent requiring correction as follows: Page l, sec

58, claim'li, for "materials" read ---ynrns---5s` and that the said *Lettersl Patent should be read wil this correction therein that the same may conform to the record of the' case in the Petent. Office l signed and sealed this 5m der'v of February, 13 19M.

Lesl e Frazer' (Seal) First Aeeistant Commissioner of Patents., 

